One of the current techniques for providing a wireless local area network which has achieved widespread use, is international standard IFO/IEC standard 8802-11, which is also ANSI/IEEE Standard 802.11 (herein Standard 802.11). This standard provides a uniform specification for a wireless local area network media access control (MAC) and physical layer (PHY) so that equipment from multiple sources works together.
The 802.11 standard is useful for wireless local area networks which may be used in a facility, such as a store, a factory, a research laboratory or a university for providing wireless communication between a stationary system, such as a wired network or a computer and mobile units. The wired network includes one or more access points which interfaced the wired network or computer to the mobile units using radio signals. The mobile units, which may include portable computers having a wireless radio add-on, personal digital assistants, bar code scanners, point of sale devices and the like, communicate with the access point to provide wireless access to the underlying system.
There is currently being developed a specification for the “Bluetooth System” for providing wireless communication over a shorter range, for example providing communication between a portable personal computer and a printer or other devices. The Bluetooth specification is intended to provide less expensive radio protocol technology for communicating over shorter ranges. The draft Bluetooth specification is available at www.Bluetooth.com.
Both the 802.11 system and the Bluetooth system operate in the same 2.4 GHz ISM radio frequency band. The devices in both systems are mobile, and may radiate spread spectrum signals over the frequency range. Accordingly, there is a possibility of the signals from one system interfering with transmissions in the other system and causing loss of data. Also, for many applications it is desirable for a mobile unit to be able to use both systems.
It is an object of the present invention to provide a dual mode mobile unit capable of operating in both the 802.11 system and in a Bluetooth system for communications between the dual mode mobile unit and other units using either system.
It is a further object of the invention to provide methods whereby 802.11 systems and Bluetooth systems can co-exist without signal interference.